There are many night time situations in which it is desirable to illuminate the water around a ship, boat or other surface vessel from the vessel itself. This is often done with powerful search lights mounted on the bridge, cabin, deck or other structure of the vessel that illuminate the upper surface of the water. However, in many cases a greater degree of illumination beneath the water surface is desired which can only be achieved if the light source is underwater. For example, divers can more safely enter the water from a vessel and climb out of the water into a vessel during the night if the area beneath the hull of the vessel near the jump point, swim step or ladder is illuminated. Night time search and rescue operations can also be facilitated by illuminating the water beneath its surface. Logs and other obstacles floating near the surface can be more easily identified and avoided during evening cruises with an underwater beam of light projecting from the bow of a vessel. Night time underwater photography is facilitated by illuminating the water beneath the surface adjacent the vessel hull. Fish and other sea life can also be attracted at night using underwater illumination. Aesthetically pleasing lighting effects can also be generated by projecting one or more beams of light laterally from the hull of a surface vessel beneath the water line so that they are readily visible to passengers and crew.
It is not practical to permanently attach underwater lights to the exterior of the hull due to the excessive drag that would be created, not to mention the severe mechanical strains on such appendages at high velocities of vessel travel. It is also tedious and cumbersome to lower lights on lines and cables from the deck of the vessel. Accordingly, thru-hull lights have been developed and used which essentially comprise a cylindrical lamp housing having a forward end with a protective, transparent, window that is mounted in water-tight fashion in a hole in the vessel hull with a conventional through hull fitting. The lamp is mounted in the housing behind the transparent window and is powered with shore power at the dock or the vessel's onboard power system when away from the dock. Numerous problems have been encountered with prior art thru-hull lights that have heretofore been commercialized for use with surface vessels. Their high heat output can damage the portion of a fiberglass hull immediately adjacent to the cylindrical lamp housing. Their beam patterns have not been optimized. The windows of the prior art thru-hull lights are subject to scratching from hull cleaning and breakage due to thermal shock and wave slap. The electrical circuits of the prior art thru-hull lights have not had any protection against water leakage, any protection against galvanic action that can lead to rapid and excessive corrosion of their metal parts, nor any power status or fault indicators.